Anyone Seen Evolution?

John R. Campbell campbejr at phu989.mms.sbphrd.com
Thu Nov 21 16:05:11 EST 1996


On Mon, 18 Nov 1996 17:02:34 -0500, Jeff Bush <jbush at afit.af.mil> wrote:
>
>On Sun, 17 Nov 1996, Greg Adcock wrote:
>
>> I smell a creationist but...
>
>Through and through!
>
>> Resistance... of hatever sort you like... insects to insecticides,
>
>Sounds like natural selection, can you expound on that.  How do I know 
> there weren't a small percent of insects that were resistant to 
>the insecticide to begin with.  My question was pointing at *observing* a 
>benifitial mutation in the genetic code.

	Actually, consider that sexual reproduction provides a certain
	number of errors in replication (heck, even fissioning has some
	copy errors; you don't find SECDED protocols common within living
	tissues) generates useful (and not so useful) variations on a
	theme.

	In species that reproduce at a higher rate the level of variation
	can be pretty high;  This provides a fairly wide gene pool where
	many little differences have arisen.

	Given environmental stresses that favor reporduction by a small
	subset of the whole pool because of a particular genetic trait
	(like penicillin and resistance) you're going to get an expansion
	of that trait.

	This isn't *entirely* true, however-  Peniccillin resistant strains
	are just that- resistant.  They are not necessarily immune (though
	they're more resistant to antibiotics than the host organism after
	a while).

	But, unless there's some kind of selection pressure applied across
	generations, a trait won't be reinforced.  In order to become a
	"selectable" trait there must be an environmental advantage to it.

	Some immunities can also be considered selectable traits, too...

	Now if anybody is crazy enough to think that anything I've said
	is authoritative, they'd better re-think that assumption...

-- 
 John R. Campbell, Speaker to Machines, Resident Heckler          soup at jtan.com
  "As a SysAdmin, yes, I CAN read your e-mail, but I DON'T get that bored!"-me
   Disclaimer:	I'm just a consultant at the bottom of the food chain, so,
		if you're thinking I speak for anyone but myself, you must
		have more lawyers than sense.




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